Phase-shift blankmask and method for fabricating the same

ABSTRACT

Provided is a phase-shift blankmask in which a phase-shift layer is formed in at least two continuous layers or a multi-layer film and an uppermost phase-shift layer included in the phase-shift layer is thinly formed to contain a small amount of oxygen (O) so as to enhance chemical resistance and durability thereof. 
     Accordingly, a phase-shift blankmask including the phase-shift layer having enhanced chemical resistance and durability with respect to a cleaning solution containing acid and basic materials, hot deionized water, or ozone water, which is used in a cleaning process that is repeatedly performed during manufacture of a photomask, may be provided using the uppermost phase-shift layer having the enhanced chemical resistance and durability. 
     Furthermore, degradation in the refractive index and degree of phase shift of the phase-shift layer, caused when the cleaning process is repeatedly performed may be prevented due to the uppermost phase-shift layer having the enhanced chemical resistance and durability. Accordingly, a phase-shift blankmask including a thin phase-shift layer can be provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 2012-0045404, filed on Apr. 30, 2012, and No.2013-0008329, filed on Jan. 25, 2013, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a phase-shift blankmask and a method offabricating the same, and more particularly, to a phase-shift blankmaskincluding a phase-shift layer having improved chemical resistance anddurability to have a thin thickness suitable for a semiconductormanufacturing process using KrF and ArF excimer lasers and a method offabricating the same.

2. Discussion of Related Art

Today, as a need for a fine circuit pattern has been accompanied by highintegration of large-scale integrated circuits (ICs), high semiconductormicrofabrication process technology has emerged as a very importantissue. In the case of a highly integrated circuit, circuit wires becomefiner for low power consumption and high-speed operations, and there isa growing technical need for a contact hole pattern for an interlayerconnection and a circuit arrangement for high integration. Thus, inorder to satisfy such demands, technology for a photomask on which anoriginal circuit pattern is recorded needs to be manufactured to befiner and to be capable of recording a more precise circuit patternthereon.

A photolithography technology has been developed to shorten an exposurewavelength by using a 436 nm g-line, a 365 nm i-line, 248 nm KrF laser,or 193 nm ArF laser in order to improve the resolution of asemiconductor circuit pattern. However, the shortening of the exposurewavelength greatly contributes to an improvement in the resolution of asemiconductor circuit pattern but deteriorates a depth of focus (DoF),thereby increasing a burden on design of an optical system including alens.

Accordingly, in order to solve this problem, a phase-shift mask has beendeveloped to improve both the resolution and DoF of a semiconductorcircuit pattern using a phase-shift layer that shifts the phase ofexposure light by 180 degrees. A phase-shift blankmask has a structurein which a phase-shift layer, a light-shielding film, and a photoresistfilm are stacked on a transparent substrate. The phase-shift blankmaskcan be used as a blankmask for realizing a high-precision minimumcritical dimension (CD) of 90 nm or less during a semiconductorphotolithography process, and particularly, can be used in the field oflithography using 248 nm KrF laser or 193 nm ArF laser and the field ofimmersion exposure lithography.

During a process of cleaning a photomask formed as a phase-shiftblankmask, a cleaning solution containing an acid material, such assulfuric acid, and a basic material, such as ammonium, have been usedbut a cleaning process using hot deionized water and ozone (O₃) waterhas recently been introduced. However, a conventional phase-shift layer,e.g., a phase-shift layer having nitrogen (N)-containing metal silicide,has a certain degree of chemical resistance to acid and basic chemicalsbut has low durability with respect to hot deionized water and ozonewater. Also, a phase-shift layer having nitrogen (N) and oxygen(O)-containing metal silicide has low durability with respect to acleaning solution containing acid and basic materials. Thus, phase-shiftlayers become thicker and thicker to compensate for variations in arefractive index and phase shift degree thereof.

As a cleaning process is repeatedly performed during manufacture of aphotomask and during use of the photomask, a thickness of a phase-shiftlayer changes, thus causing a change in the optical characteristics(e.g., a degree of phase shift, transmissivity, reflectivity, etc.) ofthe photomask. Furthermore, as the cleaning process is repeatedlyperformed, surfaces of the phase-shift layer are damaged to cause achange in surface roughness and flatness thereof. Accordingly, thedurability of the phase-shift layer is degraded, and it is thusdifficult to manufacture a reliable photomask.

SUMMARY OF THE INVENTION

The present invention is directed to a phase-shift blankmask including athin phase-shift layer having improved chemical resistance anddurability not to deteriorate (not to dissolve or corrode) due to acleaning solution containing acid and basic materials, ozone water, andhot deionized water used in a cleaning process that is repeatedlyperformed a plurality of numbers of time during manufacture of aphotomask, and a method of fabricating the same.

According to an aspect of the present invention, there is provided aphase-shift blankmask in which a phase-shift layer is disposed on atransparent substrate, wherein the phase-shift layer includes at leasttwo layers formed of different materials, wherein an uppermostphase-shift layer among the at least two layers includes at least metal,silicon (Si), oxygen (O), and nitrogen (N).

The phase-shift layer including the at least two layers may be formed incontinuous films or a multi-layer film.

The uppermost phase-shift layer included in the phase-shift layer may beformed of MoSiON, and may have a composition ratio in which content ofmolybdenum (Mo) is 1 at % to 30 at %, content of silicon (Si) is 30 at %to 80 at %, content of oxygen (O) is 0.1 at % to 20 at %, and content ofnitrogen (N) is 10 at % to 50 at %.

The uppermost phase-shift layer included in the phase-shift layer mayhave a thickness of 10 to 200.

In the phase-shift layer, a phase-shift layer disposed below theuppermost phase-shift layer may include at least a metal, silicon (Si),and nitrogen (N).

In the phase-shift layer, the phase-shift layer disposed below theuppermost phase-shift layer may be formed of MoSiN, and may have acomposition rate in which content of molybdenum (Mo) is 1 at % to 30 at%, content of silicon (Si) is 30 at % to 80 at %, and content ofnitrogen (N) is 10 at % to 50 at %.

In the phase-shift layer, the phase-shift layer disposed below theuppermost phase-shift layer may have a thickness of 300 to 1,000.

In the phase-shift layer, a ratio of a thickness of the uppermostphase-shift layer to a whole thickness of the phase-shift layer may be1% to 40%.

In the phase-shift layer, a ratio of a thickness of a phase-shift layerbelow the uppermost phase-shift layer to a thickness of the uppermostphase-shift layer may be 1:5 to 30.

The metal contained in the phase-shift layer may include at least oneselected from the group consisting of titanium (Ti), vanadium (V),cobalt (Co), nickel (Ni), zirconium (Zr), niobium (Nb), palladium (Pd),zinc (Zn), chromium (Cr), aluminum (Al), manganese (Mn), cadmium (Cd),magnesium (Mg), lithium (Li), selenium (Se), copper (Cu), molybdenum(Mo), hafnium (Hf), tantalum (Ta), and tungsten (W).

The phase-shift layer may have a transmissivity of 1% to 30% and adegree of phase shift of 170° to 190°.

The phase-shift blankmask may further include a light-shieldingfilm-forming film disposed on or below the phase-shift layer.

The light-shielding film-forming film may include a light-shielding filmand an anti-reflective layer, and has a thickness of 200 to 800.

The light-shielding film-forming film may include at least one selectedfrom the group consisting of titanium (Ti), vanadium (V), cobalt (Co),nickel (Ni), zirconium (Zr), niobium (Nb), palladium (Pd), zinc (Zn),chromium (Cr), aluminum (Al), manganese (Mn), cadmium (Cd), magnesium(Mg), lithium (Li), selenium (Se), copper (Cu), molybdenum (Mo), hafnium(Hf), tantalum (Ta), and tungsten (W), or further includes at least oneamong silicon (Si), oxygen (O), nitrogen (N), and carbon (C).

The light-shielding film-forming film may include a light-shielding filmand an anti-reflective film. The light-shielding film and theanti-reflective film may each be formed of a chrominum (Cr) compoundamong CrO, CrN, CrC, CrON, CrCO, CrCN, and CrCON.

A stacked structure of the light-shielding film-forming film and thephase-shift layer may be formed to have an optical density of 2.5 ormore at ArF and KrF exposure wavelengths.

According to another aspect of the present invention, there is provideda method of fabricating a phase-shift blankmask in which a phase-shiftlayer is disposed on a transparent substrate, wherein the phase-shiftlayer is formed in at least two layers formed of different materialsaccording to a sputtering method using one target, and an uppermostphase-shift layer included in the phase-shift layer includes at least ametal, silicon (Si), oxygen (O), and nitrogen (N).

The uppermost phase-shift layer may be formed by injecting an oxygen(O)-containing gas at a ratio of 1 vol % to 60 vol % with respect towhole gases.

After the phase-shift layer is formed, a thermal treatment process maybe performed at a temperature range of 250 to 400 for ten to sixtyminutes.

The target may include metal and silicon (Si), and a ratio between themetal and the silicon (Si) may be 1 at % to 40 at %: 99 at % to 60 at %.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent to those of ordinary skill in theart by describing in detail exemplary embodiments thereof with referenceto the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a phase-shift blankmask according toan embodiment of the present invention; and

FIG. 2 is an enlarged cross-sectional view of a portion A of FIG. 1.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed more fully with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a phase-shift blankmask 100according to an embodiment of the present invention. FIG. 2 is anenlarged cross-sectional view of a portion A of FIG. 1.

Referring to FIGS. 1 and 2, the phase-shift blankmask 100 according tothe present embodiment is a phase-shift blankmask 100 for lithographyusing ArF laser and KrF laser, in which a phase-shift layer 104, alight-shielding film-forming film 106, and a photoresist film 108 aredisposed on a transparent substrate 102.

The transparent substrate 102 has a size of 6 inch×6 inch×0.25 inch(width×height×thickness), and has a transmissivity of 90% or more at anexposure wavelength of 200 nm or less.

The phase-shift layer 104 may be formed in at least two layers havingsubstantially the same etching characteristics with respect to the sameetching material and formed of different materials using one targethaving the same composition, e.g., a target including a transition metaland silicon (Si). In the target, a ratio between a transition metal andsilicon (Si) may be 1 at % to 40 at %:99 at % to 60 at %.

The phase-shift layer 104 may be, for example, a two-layer filmincluding a first phase-shift layer 110 and a second phase-shift layer112. The first phase-shift layer 110 and the second phase-shift layer112 that constitute the phase-shift layer 104 may be formed incontinuous films or a multi-layer film including at least two layers.When the phase-shift layer 104 is a multi-layer film including at leasttwo layers, an uppermost phase-shift layer and a phase-shift layer belowthe uppermost layer are formed of different materials. In this case, thephase-shift layer below the uppermost phase-shift layer may be formed inmultiple layers that are formed using the same materials by changing acomposition ratio thereof or that are formed such that a compositionrate of a light element is changed by changing a reactive gas. Also, theuppermost layer may be formed in continuous films. Here, the continuousfilms mean films formed by changing a reactive gas injected in a plasmastate during a sputtering process. The composition of the continuousfilms changes in a depthwise direction thereof. A multi-layer film meansa stacked structure of single films, the compositions of which do notchange in a depthwise direction thereof.

The phase-shift layer 104 including the first phase-shift layer 110 andthe second phase-shift layer 112 includes a transition metal and silicon(Si), and may further include at least one material among oxygen (O),nitrogen (N), and carbon (C). The transition metal may include, forexample, at least one selected from the group consisting of titanium(Ti), vanadium (V), cobalt (Co), nickel (Ni), zirconium (Zr), niobium(Nb), palladium (Pd), zinc (Zn), chromium (Cr), aluminum (Al), manganese(Mn), cadmium (Cd), magnesium (Mg), lithium (Li), selenium (Se), copper(Cu), molybdenum (Mo), hafnium (Hf), tantalum (Ta), and tungsten (W).

The phase-shift layer 104 may be formed using a target includingmolybdenum (Mo) as a transition metal and silicon (Si). In this case,the first phase-shift layer 110 may be, for example, a nitridingphase-shift layer containing a transition metal, silicon (Si), andnitrogen (N), and be preferably formed of MoSiN which is a nitride film.The second phase-shift layer 112 may be an oxidizing phase-shift layercontaining a transition metal, silicon (Si), oxygen (O), and nitrogen(N), and be preferably formed of MoSiON which is an oxynitride film.When the first phase-shift layer 110 is formed of MoSiN, the firstphase-shift layer 110 has a composition ratio in which the content ofmolybdenum (Mo) is 1 at % to 30 at %, the content of silicon (Si) is 30at % to 80 at %, and nitrogen (N) is 10 at % to 50 at %. When the secondphase-shift layer 112 is formed of MoSiON, the second phase-shift layer112 has a composition ratio in which the content of molybdenum (Mo) is 1at % to 30 at %, silicon (Si) is 30 at % to 80 at %, oxygen (O) is 0.1at % to 20 at %, and nitrogen (N) is 10 at % to 50 at %. In this case,the content of oxygen (O) may be preferably small, e.g., 0.1 at % to 5at %.

The phase-shift layer 104 may be formed in continuous films or amulti-layer film by changing the rate of a reactive gas, changing theintensity of power to be supplied to the target, or using a sputteringprocess using a plasma-on/off state. In particular, the secondphase-shift layer 112 is formed using a sputtering method in which anoxygen-containing gas, e.g., NO, O₂, NO₂, N₂O, CO, or CO₂, is injectedat a ratio of 1 vol % to 60 vol % with respect to whole injected gases.Furthermore, the second phase-shift layer 112 may be formed in an oxygen(O) atmosphere according to a thermal treatment method using ionplating, an ion-beam, plasma surface treatment, a rapid thermal process(RTP) apparatus, a vacuum-hot plate baking apparatus, a furnace, or thelike.

The second phase-shift layer 112 is formed to prevent the phase-shiftlayer 104 from dissolving or corroding (that is, a degradationphenomenon) due to a cleaning solution used during a cleaning processincluded in a photomask manufacturing process. Conventionally, aphase-shift layer 104 is formed in a single-layer film formed of(representatively) MoSiN or MoSiON or in a multi-layer film including atleast two layers formed of the same material. However, a phase-shiftlayer formed of MoSiN has a certain degree of chemical resistance anddurability with respect to a cleaning solution containing acid and basicmaterials or a standard clean-1 (SC-1) solution, but has low chemicalresistance and durability with respect to a cleaning process using hotdeionized water and ozone water. A phase-shift layer formed of MoSiONhas a certain degree of chemical resistance and durability with respectto a cleaning process using hot deionized water and ozone water, but haslow chemical resistance and durability with respect to a cleaningsolution containing acid and basic materials or the SC-1 solution. Thus,when the phase-shift layer is damaged during the cleaning process usingsuch a cleaning solution, the phase-shift layer may decrease inthickness, increase in transmissivity, and change in a degree of phaseshift. Thus, it is difficult to achieve desired optical physicalproperties of the phase-shift layer.

The phase-shift layer according to an embodiment of the presentinvention includes the second phase-shift layer 112 formed of MoSiONcontaining a small content of oxygen (O) on an uppermost portionthereof. Such a film formed of MoSiON containing a small content ofoxygen (O) has high chemical resistance and durability with respect tonot only a cleaning solution containing acid and basic materials and acleaning solution such as the SC-1 solution but also hot deionized waterand ozone water. Thus, damage to the phase-shift layer 104 caused duringthe cleaning process may be minimized by forming the first phase-shiftlayer 110 (formed below the second phase-shift layer 112) as a filmformed of MoSiN and forming the second phase-shift layer 112 which is anuppermost layer as a film formed of MoSiON containing a small content ofoxygen (O), thereby reducing a whole thickness of the phase-shift layer104.

After the phase-shift layer 104 is formed, a thermal treatment processmay be performed on the phase-shift layer 104 to improve physicalproperties thereof if needed. The thermal treatment process may beperformed at temperature range of 250 to 400 for 10 to 60 minutes.

The first phase-shift layer 110 has a thickness of 300 to 1,000,preferably has a thickness of 500 to 700 when the first phase-shiftlayer 110 is used as a phase-shift layer for ArF lithography, andpreferably has a thickness of 700 to 1,000 when the first phase-shiftlayer 110 is used as a phase-shift layer for KrF lithography. The secondphase-shift layer 112 has a thickness of 10 to 200, and preferably, athickness of 20 to 100. A ratio of the thickness of the secondphase-shift layer 112 is 1% to 40% (preferably, 1% to 15%) to the wholethickness of the phase-shift layer 104. A ratio of the thickness of thefirst phase-shift layer 110 to the thickness of the second phase-shiftlayer 112 is preferably 1:5 to 30. When the thickness of the secondphase-shift layer 112 exceeds 40% of the whole thickness of thephase-shift layer 104, the thickness of the first phase-shift layer 110may be reduced to achieve desired thickness and transmissivity. In thiscase, the refractive index and degree of phase shift of the phase-shiftlayer 104 may be degraded with respect to an ArF or KrF exposurewavelength. When the first phase-shift layer 110 is formed to a thickthickness so as to compensate for such degradation, it is difficult toform a fine pattern of the phase-shift layer 104, thereby preventingdesired optical and physical properties of a phase-shift layer patternfrom being achieved.

The phase-shift layer 104 has a transmissivity of 1% to 30%, andpreferably, a transmissivity of 6% to 8%. The phase-shift layer 104 hasa degree of phase shift of 170° to 190°, and preferably, a degree ofphase shift of 180°.

The light-shielding film-forming film 106 may be disposed on or belowthe phase-shift layer 104. The light-shielding film-forming film 106 isformed of a metal film. The light-shielding film-forming film 106 may beformed of at least one selected from the transition metal groupconsisting of titanium (Ti), vanadium (V), cobalt (Co), nickel (Ni),zirconium (Zr), niobium (Nb), palladium (Pd), zinc (Zn), chromium (Cr),aluminum (Al), manganese (Mn), cadmium (Cd), magnesium (Mg), lithium(Li), selenium (Se), copper (Cu), molybdenum (Mo), hafnium (Hf),tantalum (Ta), and tungsten (W), and may further include at least oneamong silicon (Si), oxygen (O), nitrogen (N), and carbon (C) to themetal material. The light-shielding film-forming film 106 is preferablyformed of a material having etch selectivity with respect to thephase-shift layer 104, e.g., a chrome (Cr) compound selected from thegroup consisting of CrO, CrN, CrC, CrON, CrCO, CrCN, and CrCON.

The light-shielding film-forming film 106 may be formed in asingle-layer film or a multi-layer film. For example, thelight-shielding film-forming film 106 may further include a layer forcontrolling the reflectivity and stress of a rear surface of the metalfilm. If the light-shielding film-forming film 106 has, for example, atwo-layer structure, a lower layer and an upper layer of the two-layerstructure may be a light-shielding film configured to mainly blockexposure light and an anti-reflective layer configured to lower thereflectivity of exposure light, respectively. If the metal film isformed in a multi-layer film, an outermost surface layer preferably hasa lower reflectivity at an exposure wavelength than lower layers.

The light-shielding film-forming film 106 has a thickness of 200 to 800,and more preferably, a thickness of 400 to 600. The metal film cannotsubstantially block exposure light when the thickness thereof is 200 orless, and a resolution and precision for realizing an auxiliary shapepattern are low due to a large thickness of the metal film when thethickness thereof is 800 or more. In a stacked structure of thephase-shift layer 104 and the light-shielding film-forming film 106, anoptical density is 2.5 or more and preferably 3.0 to 5 at ArF and KrFexposure wavelengths. The light-shielding film-forming film 106 has asurface reflectivity of 10% to 30% at ArF and KrF exposure wavelengths.

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Theseembodiments are provided so that this disclosure will be thorough andcomplete and will fully convey the concept of the invention to thoseskilled in the art. The exemplary embodiments should be thus consideredin descriptive sense only and not for purposes of limitation. It wouldbe appreciated by those of ordinary skill in the art that changes may bemade in these exemplary embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

EMBODIMENTS

Design of Phase-Shift Layer

The phase-shift layer 104 according to an embodiment of the presentinvention was formed on the transparent substrate 102, in a two-layerstructure including the first phase-shift layer 110 formed of MoSiN andthe second phase-shift layer 112 formed of MoSiON.

The phase-shift layer 104 was formed in various forms as shown in Table1 by using a DC magnetron sputtering equipment including a single targetformed of MoSi and injecting nitrogen (N₂) gas and NO gas among oxygen(O)-containing gases as reactive gases.

For the phase-shift layer 104, the reactive gases were injected whilechanging a rate of the N₂ gas within a range of 30 vol % to 80 vol % andchanging a rate of the NO gas within a range of 0 vol % to 80 vol %. Thephase-shift layer 104 was formed to have a whole thickness having arange of 650±20 so that the transmissivity thereof may be approximately5.8% to 6.2% at a wavelength of 193 nm. In this case, the secondphase-shift layer 112 was formed to a thickness of about 50.

Phase-shift layers according to comparative examples presented tocompare optical and physical properties thereof with those of thephase-shift layer 104 according to the embodiment of the presentinvention were each formed in a single layer formed of MoSiN. Similar tothe phase-shift layer 104 according to the embodiment of the presentinvention, the phase-shift layers according to the comparative exampleswere formed by using a DC magnetron sputtering equipment including atarget formed of MoSi and injecting nitrogen (N₂) gas as a reactive gaswithin a range of 30 vol % to 80 vol % of whole gases. The phase-shiftlayers according to the comparative examples were formed to each have awhole thickness of 650±20 so that transmissivities thereof may be 5.8%to 6.2% at a wavelength of 193 nm.

A variation in a degree of phase shift of each of the phase-shift layersformed according to the embodiment of the present invention and thecomparative examples was measured using the MPM-193 tool, and avariation in transmissivity of each of these phase-shift layers wasmeasured using the N&K analyzer.

TABLE 1 <Degrees of phase shift and transmissivities of phase-shiftlayers> First-layer film Second-layer film Degree of N₂ Ratio (vol %) NORatio (vol %) phase shift (°) Transmissivity (%) Embodiment No. TargetN₂/(Ar + N₂) NO/(Ar + N₂+ NO) @193 nm @193 nm Embodiment MoSi 70  0179.8 5.87 1 Embodiment 70 10 180.1 6.03 2 Embodiment 70 30 180.3 6.04 3Embodiment 70 60 179.7 6.01 4 Embodiment 75 60 179.9 6.02 5 ComparativeMoSi 80 — 180.2 5.81 Example 1 Comparative 75 — 180.3 5.94 Example 2Comparative 70 — 179.8 6.16 Example 3

In the case of phase-shift layers according to embodiments 2 to 4 inwhich an uppermost phase-shift-layer was thinly formed using MoSiONamong phase-shift layers according to embodiments of the presentinvention, a degree of phase shift was 180°±0.3° and transmissivity was6%±0.4% at a wavelength of 193 nm. That is, the phase-shift layersaccording to embodiments 2 to 4 exhibited desired performances.

Ozone Water Evaluation

An ozone water evaluation was performed on the phase-shift layers formedaccording to the embodiments of the present invention and thecomparative examples. A photomask formed using a blankmask is repeatedlycleansed using ozone water during a manufacture process thereof. Duringthe cleaning process, the chemical resistance of the phase-shift layeris important. The concentration of the ozone water used for the ozonewater evaluation was 80 ppm, and the cleaning process was performed oneach of the phase-shift layers formed according to the embodiments ofthe present invention and the comparative examples fifteen times. Then,variations in the degrees of phase shift and transmissivities of thephase-shift layers were measured before and after the cleaning process.

TABLE 2 <A result of measuring variations in degrees of phase shift andtransmissivities measured before and after cleaning process using ozonewater> @ 193 nm After Cleaning process was Before cleaning performedEmbodiment No. process fifteen times delta Embodiment Transmissivity5.87 5.97 0.10 1 (%) Phase (°) 179.8 178.8 1.0 Embodiment Transmissivity6.03 6.10 0.07 2 (%) Phase (°) 180.1 179.3 0.8 Embodiment Transmissivity6.04 6.07 0.03 3 (%) Phase (°) 180.3 180.1 0.2 Embodiment Transmissivity6.01 6.06 0.05 4 (%) Phase (°) 179.7 179.1 0.6 Embodiment Transmissivity6.02 6.08 0.06 5 (%) Phase (°) 179.9 179.4 0.5 ComparativeTransmissivity 5.81 6.30 0.49 Example 1 (%) Phase (°) 180.2 172.0 7.2Comparative Transmissivity 5.94 6.31 0.37 Example 2 (%) Phase (°) 180.3174.7 5.6 Comparative Transmissivity 6.16 6.41 0.25 Example 3 (%) Phase(°) 179.8 175.6 4.2

After the cleaning process using the ozone water was performed on thephase-shift layers (according to embodiments 2 to 4 in which anuppermost phase-shift layer was thinly formed of MoSiON among thephase-shift layers the embodiments of the present invention) fifteentimes, variations in the degrees of phase shift were 0.2° to 0.8° andvariations in transmissivities were 0.03% to 0.07%, at a wavelength of193 nm.

In contrast, after the cleaning process using the ozone water wasperformed on the phase-shift layers (which were each a single filmformed of MoSiN according to the comparative examples) fifteen times,variations in the degrees of phase shift were 1.0° to 7.2° andvariations in transmissivities were 0.1% to 0.49% at a wavelength of 193nm. This is understood as results when the phase-shift layers formed ofMoSiN were dissolved in the ozone or deteriorated due to the ozone waterused during the cleaning process.

Thus, as the second phase-shift layer 112 which is an uppermost layer ofthe phase-shift layer 104 was thinly formed of MoSiON as in theembodiments of the present invention, a variation in the degree of phaseshift was 4° or less and a variation in transmissivity was 0.2% or less.Accordingly, it means that the phase-shift layer 104 according to theembodiment of the present invention has high chemical resistance anddurability with respect to ozone water.

SPM Evaluation (SPM: H₂SO₄+H₂O₂)

An SPM evaluation was performed on phase-shift layers formed accordingto embodiments of the present invention and comparative examples. TheSPM evaluation is a cleaning process performed to remove a resist layerduring manufacture of a photomask formed using a blankmask. The chemicalresistances of the phase-shift layers are particularly important duringthe cleaning process. In the SPM evaluation, a mixed solution of H₂SO₄and H₂O₂ was used (volume ratio: H₂SO₄:H₂O₂=10:1) (hereinafter referredto as SPM solution), a cleaning process was performed three times at atemperature of about 90 for ten minutes, and variations in the degree ofphase shift and transmissivity were measured before and after thecleaning process.

TABLE 3 <A result of measuring degrees of phase shift andtransmissivities according to a number of times that a cleaning processusing the SPM solution was performed> @ 193 nm After cleaning processwas Before cleaning performed Embodiment No. process three times DeltaEmbodiment Transmissivity 5.87 5.96 0.09 1 (%) Phase (°) 179.8 178.7 1.1Embodiment Transmissivity 6.03 6.08 0.05 2 (%) Phase (°) 180.1 179.5 0.6Embodiment Transmissivity 6.04 6.06 0.02 3 (%) Phase (°) 180.3 180.2 0.1Embodiment Transmissivity 6.01 6.05 0.04 4 (%) Phase (°) 179.7 179.3 0.4Embodiment Transmissivity 6.02 6.06 0.04 5 (%) Phase (°) 179.9 179.5 0.4Comparative Transmissivity 5.81 6.27 0.46 Example 1 (%) Phase (°) 180.2172.3 6.9 Comparative Transmissivity 5.94 6.29 0.35 Example 2 (%) Phase(°) 180.3 174.2 5.2 Comparative Transmissivity 6.16 6.40 0.24 Example 3(%) Phase (°) 179.8 175.9 3.9

After a cleaning process using the SPM solution was performed on thephase-shift layers (according to embodiments 2 to 4 in which anuppermost phase-shift-layer was thinly formed using MoSiON among thephase-shift layers according to the embodiments of the presentinvention) three times, a variation in the degree of phase shift was0.1° to 0.6° and a variation in transmissivity was 0.02% to 0.05%, at awavelength of 193 nm.

In contrast, after the cleaning process using the SPM solution wasperformed on the phase-shift layers (which were each a single filmformed of MoSiN according to the comparative examples) three times, avariation in the degree of phase shift was 1.1° to 6.9° and a variationin transmissivity was 0.09% to 0.46%, at a wavelength of 193 nm.

Thus, in the case of the phase-shift layer 104 according to anembodiment of the present invention in which the second phase-shiftlayer 112 was thinly formed using MoSiON as an uppermost layer of aphase-shift layer as in the embodiments of the present invention, avariation in the degree of phase shift was 4° or less and a variation intransmissivity was 0.2 at % or less. Thus, the phase-shift layer 104according to the embodiment of the present invention has high chemicalresistance and durability with respect to the SPM solution.

SC-1 Evaluation (SC-1: NH₄OH:H₂O₂:H₂O)

The SC-1 evaluation was performed on phase-shift layers formed accordingto embodiments of the present invention and comparative examples. TheSC-1 evaluation was performed to evaluate the chemical resistance of aMoSi-based compound with respect to ammonium water used during acleaning process during manufacture of a photomask formed using ablankmask. In the SC-1 evaluation, a mixed solution of NH₄OH, H₂O₂, andH₂O (volume ratio: NH₄OH:H₂O₂:H₂O=1:1:3) was used. The SC-1 evaluationwas performed under harsh conditions, at a room temperature of about 23for two hours. Then, variations in degrees of phase shift andtransmissivities were measured before and after the cleaning process.

TABLE 4 <A result of measuring degrees of phase shift andtransmissivities when a cleaning process using the SC-1 solution wasperformed> @ 193 nm Before cleaning After cleaning Embodiment No.process process delta Embodiment Transmissivity 5.87 6.18 0.31 1 (%)Phase (°) 179.8 178.7 1.1 Embodiment Transmissivity 6.03 6.20 0.17 2 (%)Phase (°) 180.1 178.6 1.5 Embodiment Transmissivity 6.04 6.17 0.13 3 (%)Phase (°) 180.3 179.1 1.2 Embodiment Transmissivity 6.01 6.22 0.21 4 (%)Phase (°) 179.7 177.9 1.8 Embodiment Transmissivity 6.02 6.24 0.22 5 (%)Phase (°) 179.9 178.1 1.8 Comparative Transmissivity 5.81 7.67 1.86Example 1 (%) Phase (°) 180.2 151.8 28.4 Comparative Transmissivity 5.947.21 1.27 Example 2 (%) Phase (°) 180.3 161.6 18.7 ComparativeTransmissivity 6.16 7.18 1.02 Example 3 (%) Phase (°) 179.8 164.5 15.3

After the cleaning process using the SC-1 solution was performed on thephase-shift layers according to embodiments 2 to 4 in which an uppermostphase-shift layer was thinly formed of MoSiON among the phase-shiftlayers according to the embodiments of the present invention, variationsin the degrees of phase shift were 1.2° to 1.8° and variations intransmissivities were 0.13% to 0.22%, at a wavelength of 193 nm.

In contrast, after the cleaning process using the SC-1 solution wasperformed on the phase-shift layers which were each a single film formedof MoSiN according to the comparative examples, variations in thedegrees of phase shift were 1.1° to 28.4° and variations intransmissivities were 0.31% to 1.86% at a wavelength of 193 nm.

Thus, as an uppermost layer of the phase-shift layer 104 was thinlyformed of MoSiON as an uppermost layer of a phase-shift layer as in theembodiments of the present invention, a variation in the degree of phaseshift was 4° or less and a variation in transmissivity was 0.2% or less.Accordingly, it means that the phase-shift layer 104 according to theembodiment of the present invention has high chemical resistance anddurability with respect to the SC-1 solution.

HOT-DIW Evaluation

An evaluation of a cleaning process using hot deionized water (HOT-DIW)(hereinafter referred to as HOT-DIW evaluation) was performed onphase-shift layers formed according to embodiments of the presentinvention and comparative examples. The HOT-DIW evaluation was performedunder condition in which the phase-shift layers were immersed indeionized water (DIW) of 95 for fifty minutes, and variations in degreesof phase shift and transmissivities were measured before and after thecleaning process.

TABLE 5 <A result of measuring variations in degrees of phase shift andtransmissivities according to the HOT-DIW evaluation> @ 193 nm Beforecleaning After cleaning Embodiment No. process process delta EmbodimentTransmissivity 5.87 6.47 0.60 1 (%) Phase (°) 179.8 175.7 4.1 EmbodimentTransmissivity 6.03 6.27 0.24 2 (%) Phase (°) 180.1 177.8 2.3 EmbodimentTransmissivity 6.04 6.23 0.19 3 (%) Phase (°) 180.3 178.5 1.8 EmbodimentTransmissivity 6.01 6.28 0.27 4 (%) Phase (°) 179.7 177.1 2.6 EmbodimentTransmissivity 6.02 6.30 0.28 5 (%) Phase (°) 179.9 177.2 2.7Comparative Transmissivity 5.81 7.98 2.17 Example 1 (%) Phase (°) 180.2148.8 31.4 Comparative Transmissivity 5.94 7.78 1.84 Example 2 (%) Phase(°) 180.3 154.2 26.1 Comparative Transmissivity 6.16 7.68 1.52 Example 3(%) Phase (°) 179.8 159.4 20.4

After the cleaning process using the HOT-DOW was performed on aphase-shift layer in which an uppermost phase-shift layer was thinlyformed of MoSiON among the phase-shift layers according to theembodiments of the present invention, a variation in the degree of phaseshift was 1.8° to 2.7° and a variation in transmissivity was 0.19% to0.28%, at a wavelength of 193 nm.

In contrast, after the cleaning process using the HOT-DIW was performedon the phase-shift layers that were each a single film formed of MoSiNaccording to the comparative examples, a variation in the degree ofphase shift was 4.1° to 31.4° and a variation in transmissivity was 0.6%to 2.17%, at a wavelength of 193 nm.

Thus, as an uppermost layer of the phase-shift layer 104 was thinlyformed of MoSiON as an uppermost layer of a phase-shift layer as in theembodiments of the present invention, a variation in the degree of phaseshift was 4° or less and a variation in transmissivity was 0.2% or less.Accordingly, it means that the phase-shift layer 104 according to theembodiment of the present invention has high chemical resistance anddurability with respect to the HOT-DIW.

As shown in Tables 2 to 4, it means that the phase shift layers having atwo-layer structure according to the embodiments of the presentinvention, e.g., the phase-shift layer 104 including the secondphase-shift layer 112 which is an oxidizing uppermost layer formed ofMoSiON to a thickness of about 50, had higher chemical resistance anddurability than the phase-shift layers which were each a nitridingsingle film formed of MoSiN according to the comparative examples.

Also, it was noted that the phase-shift layer formed when a ratio of NOgas to whole injected gases was about 30 vol % among gases used to formuppermost phase-shift layers had highest physical properties than theother phase-shift layers according to the embodiments of the presentinvention.

As described above, according to an embodiment of the present invention,a phase-shift layer is formed in at least two continuous films or amulti-layer film, and an uppermost phase-shift layer included in thephase-shift layer is formed to a thin thickness and contains a smallamount of oxygen (O) to have enhanced chemical resistance and durabilitythereof.

Thus, a phase-shift blankmask including a phase-shift layer havingenhanced chemical resistance and durability with respect to a cleaningsolution containing acid and basic materials, hot deionized water, orozone water, which is used in a cleaning process that is repeatedlyperformed during manufacture of a photomask, may be provided using theuppermost phase-shift layer having the enhanced chemical resistance anddurability.

Furthermore, degradation in the refractive index and degree of phaseshift of the phase-shift layer, caused when the cleaning process isrepeatedly performed may be prevented due to the uppermost phase-shiftlayer having the enhanced chemical resistance and durability.Accordingly, a phase-shift blankmask including a thin phase-shift layercan be provided.

It will be apparent to those skilled in the art that variousmodifications can be made to the above-described exemplary embodimentsof the present invention without departing from the spirit or scope ofthe invention. Thus, it is intended that the present invention coversall such modifications provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A phase-shift blankmask in which a phase-shiftlayer is disposed on a transparent substrate, wherein the phase-shiftlayer comprises at least two layers formed of different materials,wherein an uppermost phase-shift layer among the at least two layerscomprises at least a metal, silicon (Si), oxygen (O), and nitrogen (N).2. The phase-shift blankmask of claim 1, wherein the phase-shift layerincluding the at least two layers is formed in continuous films or amulti-layer film.
 3. The phase-shift blankmask of claim 1, wherein theuppermost phase-shift layer included in the phase-shift layer is formedof MoSiON, and has a composition ratio in which content of molybdenum(Mo) is 1 at % to 30 at %, content of silicon (Si) is 30 at % to 80 at%, content of oxygen (O) is 0.1 at % to 20 at %, and content of nitrogen(N) is 10 at % to 50 at %.
 4. The phase-shift blankmask of claim 1,wherein the uppermost phase-shift layer included in the phase-shiftlayer has a thickness of 10 to
 200. 5. The phase-shift blankmask ofclaim 1, wherein, in the phase-shift layer, a phase-shift layer disposedbelow the uppermost phase-shift layer comprises at least a metal,silicon (Si), and nitrogen (N).
 6. The phase-shift blankmask of claim 5,wherein, in the phase-shift layer, the phase-shift layer disposed belowthe uppermost phase-shift layer is formed of MoSiN, and has acomposition rate in which content of molybdenum (Mo) is 1 at % to 30 at%, content of silicon (Si) is 30 at % to 80 at %, and content ofnitrogen (N) is 10 at % to 50 at %.
 7. The phase-shift blankmask ofclaim 5, wherein, in the phase-shift layer, the phase-shift layerdisposed below the uppermost phase-shift layer has a thickness of 300 to1,000.
 8. The phase-shift blankmask of claim 1, wherein, in thephase-shift layer, a ratio of a thickness of the uppermost phase-shiftlayer to a whole thickness of the phase-shift layer is 1% to 40%.
 9. Thephase-shift blankmask of claim 1, wherein, in the phase-shift layer, aratio of a thickness of a phase-shift layer below the uppermostphase-shift layer to a thickness of the uppermost phase-shift layer is1:5 to
 30. 10. The phase-shift blankmask of claim 1, wherein the metalcontained in the phase-shift layer comprises at least one selected fromthe group consisting of titanium (Ti), vanadium (V), cobalt (Co), nickel(Ni), zirconium (Zr), niobium (Nb), palladium (Pd), zinc (Zn), chromium(Cr), aluminum (Al), manganese (Mn), cadmium (Cd), magnesium (Mg),lithium (Li), selenium (Se), copper (Cu), molybdenum (Mo), hafnium (Hf),tantalum (Ta), and tungsten (W).
 11. The phase-shift blankmask of claim1, wherein the phase-shift layer has a transmissivity of 1% to 30% and adegree of phase shift of 170° to 190°.
 12. The phase-shift blankmask ofclaim 1, further comprising a light-shielding film-forming film disposedon or below the phase-shift layer.
 13. The phase-shift blankmask ofclaim 12, wherein the light-shielding film-forming film comprises alight-shielding film and an anti-reflective layer, and has a thicknessof 200 to
 800. 14. The phase-shift blankmask of claim 12, wherein thelight-shielding film-forming film comprises at least one selected fromthe group consisting of titanium (Ti), vanadium (V), cobalt (Co), nickel(Ni), zirconium (Zr), niobium (Nb), palladium (Pd), zinc (Zn), chromium(Cr), aluminum (Al), manganese (Mn), cadmium (Cd), magnesium (Mg),lithium (Li), selenium (Se), copper (Cu), molybdenum (Mo), hafnium (Hf),tantalum (Ta), and tungsten (W), or further comprises at least one amongsilicon (Si), oxygen (O), nitrogen (N), and carbon (C) to the metal. 15.The phase-shift blankmask of claim 12, wherein the light-shieldingfilm-forming film comprises a light-shielding film and ananti-reflective film, wherein the light-shielding film and theanti-reflective film are each formed of a chrominum (Cr) compound amongCrO, CrN, CrC, CrON, CrCO, CrCN, and CrCON.
 16. The phase-shiftblankmask of claim 12, wherein a stacked structure of thelight-shielding film-forming film and the phase-shift layer is formed byan optical density of 2.5 or more at ArF and KrF exposure wavelengths.17. A method of fabricating a phase-shift blankmask in which aphase-shift layer is disposed on a transparent substrate, wherein thephase-shift layer is formed in at least two layers formed of differentmaterials according to a sputtering method using one target, and anuppermost phase-shift layer included in the phase-shift layer comprisesat least a metal, silicon (Si), oxygen (O), and nitrogen (N).
 18. Themethod of claim 17, wherein the uppermost phase-shift layer is formed byinjecting an oxygen (O)-containing gas at a ratio of 1 vol % to 60 vol %with respect to whole gases.
 19. The method of claim 17, wherein, afterthe phase-shift layer is formed, a thermal treatment process isperformed at a temperature range of 250 to 400 for ten to sixty minutes.20. The method of claim 17, wherein the target comprises a metal andsilicon (Si), wherein a ratio between the metal and the silicon (Si) is1 at % to 40 at %:99 at % to 60 at %.